It is well known that diesel engines pose particular problems when operating in an atmosphere or environment containing natural gas or other volatile hydrocarbons. This often occurs in oil fields or chemical plants where engines, operating in and around a volatile fuel source, draw feral gas into the engine's intake manifold resulting in uncontrollable engine revving and possible catastrophic engine failure.
Numerous devices have been developed which block air induction into the air intake of an overrevving diesel engine including; RIGSAVER.sub..TM., AMONT.sub..TM., CHALMATIC.sub..TM., and GATOR.sub..TM.. These devices when actuated rapidly shutdown all or most of the engine's intake air with a valve member thereby starving the engine of oxygen required for internal combustion resulting in almost immediate engine cessation. While the devices provide an effective shutdown system the means by which the shutdown devices block engine intake air at a moment when the engine is operating at high RPMs leads to a considerable low and immediate evacuation of the engine's air intake system downstream from the shutdown device. The evacuation though necessary to rapidly shut down the engine leads to sometimes devastating effects upon the engine's turbocharger seals and thrust washers. After an emergency shutdown the turbocharger is sometimes incapacitated until the damaged parts can be replaced. Therefore, a need exist to shutdown a diesel engine by blocking the engine's air intake while not damaging the turbocharger or other related parts. The present invention provides a means for not only shutting down the diesel engine by blocking the air intake but also doing so without damaging these parts.
The invention utilizes a tubing connection between the engine's exhaust manifold and the engine's intake manifold downstream from the shutdown device. The tubing connection includes a check valve to prevent the flow of exhaust gases into the intake manifold until the vacuum level in the intake manifold reaches a desired level. When the shutdown device blocks intake air and a vacuum develops in the intake tubing between the shutdown device and the engine, exhaust gases will enter the evacuated intake manifold preventing a damaging vacuum from forming while also not introducing any oxygen into the engine's intake manifold thereby allowing the engine to be shutdown. After the vacuum is depleted the check valve returns to the closed position blocking the flow of exhaust gases into the intake manifold.